Invasive medical probes are used in a variety of medical procedures, such as cardiac electrophysiological (EP) mapping and ablation. For example, U.S. Pat. No. 7,740,629, whose disclosure is incorporated herein by reference, describes an ablation catheter including an elongate carrier. A first loop is arranged at, or adjacent, a distal end of the carrier. At least one sensing electrode is carried on the first loop for sensing irregular electrical activity in a patient's body. At least one further loop is arranged proximally relative to the first loop on the carrier in a fixed orientation relative to the first loop. At least one ablating electrode is carried on the second loop for ablating a site of the patient's body where irregular electrical activity occurs.
U.S. Patent Application Publication 2012/0245665, whose disclosure is incorporated herein by reference, describes an electrical lead for a cardiac device including a body having a distal end sized for insertion through a catheter, first and second electrodes extending through the body, with each electrode terminating in a tip having proximal and distal ends and arranged to extend to an area of cardiac tissue. The tips include a fully insulated portion on the proximal and distal ends measuring in a range between 5 percent and 40 percent of the lengths of the tips, and further include an uninsulated intermediate section. The tip of the second electrode includes a helical section surrounding the first electrode and has an insulated portion on an inwardly facing portion surface facing toward the first electrode. The tip of the second electrode also includes a fully insulated portion on the proximal and distal ends measuring in the same or similar percentage range.
A publication entitled “Complete Isolation of Left Atrium Surrounding the Pulmonary Veins: New Insights from the Double-Lasso Technique in Paroxysmal Atrial Fibrillation”, Circulation, Vol. 110, No. 15, Oct. 12, 2004, pages 2090-2096, which is incorporated herein by reference, describes a method where Paroxysmal atrial fibrillation (PAF) can be eliminated with continuous circular lesions (CCLs) around the pulmonary veins (PVs).